COLUMBUS, Ohio (AP) — The number of mumps cases in the Ohio State University outbreak has climbed to 32 as officials try to trace how the people involved acquired the viral infection.

Columbus Public Health reports the four cases added to the count Wednesday involve three students and one staff member.

Of the 32 people infected, 26 are students, two are staff members and one is a student’s relative. Health officials say the other three cases involve people who don’t study or work at Ohio State but have links to the university community.

The confirmed cases involve 13 women and 19 men. They range in age from 18 to 48. Three of them were hospitalized for at least one day.

Mumps is a contagious infection that often starts with fever, fatigue and body aches.